The present invention relates to a dual-circuit pressure control valve for hydraulic brake systems including two control pistons arranged in parallel side by side and each assigned to a different one of two brake circuits, the control pistons being loaded by a preloading force which increases at the control piston of the operable brake circuit upon a pressure failure in one brake circuit.
In a known pressure control valve of the aforementioned type (German Pat. DE-OS No. 27 48 699), one half of the force of a common preloading helical spring is transmitted to the point of application at the upper end surface of each of the pistons. Upon failure of one brake circuit, the distribution element bears against the control piston remaining in its rest position due to the failure and is tilted by the piston in operation, so that the latter piston is loaded by the entire spring force resulting in an increase of the changeover point in the associated brake circuit. This tilting movement of the distribution element is detrimental in many cases. For instance, the distribution element is guided by a foot in an axial bore and becomes jammed therein when tilted and the spring is loaded unsymmetrically due to the tilting and, hence, requires a guidance which in turn tends to be jammed.